The elisa reader is the enzyme-linked immunoassay. It is a special instrument for enzyme-linked immunosorbent assay, also called microplate detector. It can be simply divided into two categories: semi-automatic and fully automatic, but their working principles are basically the same. The core is a colorimeter, in other words, colorimetric analysis is used. The determination generally requires the final volume of the test solution to be less than 250μL, and the test cannot be completed with a general photoelectric colorimeter, so there are special requirements for the photoelectric colorimeter in the elisa reader.